Recently, various services that utilize position information have been developed, such as a security service capable of checking present positions and action histories of seniors and young people using position information.
Also, such services have been launched that provide information more specifically related to activities and inclinations of the owner of the mobile phone, utilizing for example a view history of web browsers, in addition to the position information.
However, the provision of the position information and user activity data such as the web view history by the general user to a service leads to a risk that the privacy of the general user may endlessly leak to operators of the service provider and information users who utilize the user activity data from the service.
Refraining from providing with the user activity data is the simplest way that the general user could keep his/her highly private activity confidential, however in this case other users can notice the fact that the general user is performing an activity that is so private that he or she needs to keep a secret. Accordingly, it is requires such measures that other users can not recognize that the general user is not providing the user activity data.
To cope with the foregoing problem, user activity data conceal systems have been proposed. For example, a technique has been proposed that returns pseudo positioning information designated by the general user in advance with a place name or the like, in response to a reference of position information from a specific service (for example, patent document 1).
Also, a technique has been proposed that returns a pseudo route calculated on the basis of the current position of the general user and the designated destination, in response to a reference of position information from a specific service, thereby concealing information with reduced contradiction in information between before and after the concealing (for example, patent document 2).